The prize was awarded to William G. Kaelin Jr., Peter J. Ratcliffe, and Gregg L. Semenza for their work in discovering how cells sense and to adapt to oxygen availability.

The Nobel Prize in Physiology or Medicine was jointly awarded to three scientists — William G. Kaelin Jr., Peter J. Ratcliffe, and Gregg L. Semenza — for their work on how cells sense and adapt to oxygen availability.

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Animals need oxygen for the conversion of food into useful energy. The fundamental importance of oxygen has been understood for centuries, but how cells adapt to changes in levels of oxygen has long been unknown.

William G. Kaelin Jr., Sir Peter J. Ratcliffe, and Gregg L. Semenza discovered how cells can sense and adapt to changing oxygen availability. They identified molecular machinery that regulates the activity of genes in response to varying levels of oxygen.

The seminal discoveries by this year’s Nobel Laureates revealed the mechanism for one of life’s most essential adaptive processes. They established the basis for our understanding of how oxygen levels affect cellular metabolism and physiological function. Their discoveries have also paved the way for promising new strategies to fight anemia, cancer and many other diseases.

– Nobel Prize, press release.

They have uncovered the mechanisms surrounding the body’s response to low oxygen conditions. When the body is deprived of oxygen, there is a rise in the hormone erythropoietin (EPO) – this then boosts the production of red blood cells, which carry oxygen around the body.

When oxygen levels drop, the levels of a protein complex (dubbed HIF) increase. Under normal oxygen conditions, HIF is rapidly broken down – but under low oxygen conditions it instead builds up. Crucially this complex binds to segments of DNA near the gene for EPO, regulating the expression of the gene and hence levels of EPO.

The three researchers also revealed how HIF is modified under normal conditions so that it is rapidly broken down inside cells, revealing the key role of oxygen-sensitive enzymes.

The 2019 Nobel Prize in Physiology or Medicine is the 110th prize in the category that has been awarded since 1901. The Karolinska Institutet said in a statement the trio should share equally the 9 million kronor (around $1.2 million Cdn) cash award.